Factor I (Fibrinogen) Deficiency
Factor II Deficiency
Factor V Deficiency
Combined Factor V and Factor VIII Deficiency

Factor I deficiency is an autosomal recessive inherited coagulation disorder caused by a defect or lack of fibrinogen in the blood, which plays an important role in blood clotting. When fibrinogen is not functioning properly, when it is absent or at a very low level, it is difficult to form a blood clot.

Factor II (prothrombin) deficiency usually is an autosomal recessive inherited coagulation disorder caused by a defect or lack of prothrombin in the blood. Factor II deficiency may also be acquired later in life. Severe liver disease can slow down or stop prothrombin production.

In Factor II deficiency, there is a reduced amount of prothrombin in the blood, or the prothrombin does not function properly. Normally, Factor Xa, another blood clotting protein, converts prothrombin to thrombin which continues a complex clotting chain reaction that ultimately results in a clot. Without prothrombin, the process stops prematurely and a clot does not form.

Factor V (proaccelerin) deficiency is an autosomal recessive inherited coagulation disorder caused by a defect or lack of proaccelerin in the blood that helps blood to clot.

Combined Factor V and Factor VIII deficiency is an autosomal recessive inherited coagulation disorder. It is completely separate from Factor V deficiency and FVIII deficiency. Factor V and Factor VIII are proteins in the blood that promote clotting. In this disorder, levels of both factors are lower, between 5% and 20% of normal levels.

Factor VII (proconvertin) deficiency is usually an autosomal recessive inherited coagulation disorder caused by a defect or lack of proconvertin in the blood that helps blood to clot.

Factor VII deficiency may also be acquired through liver disease, low levels of vitamin K, or from other problems with absorption. The acquired form of the disorder can also develop in patients who take anti-coagulants.

Factor X deficiency is an autosomal recessive inherited coagulation disorder caused by a defect or lack of Factor X in the blood which helps blood to clot. The disorder is one of the rarest inherited clotting disorders. Most people with Factor X deficiency are asymptomatic.

Factor XI deficiency (plasma thromboplastin antecedent, PTA) is an autosomal recessive inherited coagulation disorder caused by a defect or lack of PTA in the blood that helps blood to clot.

Factor XIII (fibrin stabilization factor) deficiency is an autosomal recessive inherited coagulation disorder caused by a defect or lack of Factor XIII which helps blood to clot.